The ability to extract meaning from experience by abstracting categories and other generalized principles is a foundation of cognition. It is disrupted in neuropsychiatric diseases like autism and schizophrenia. During the last funding period, we used novel behavioral paradigms to identify neural correlates of categories in the prefrontal cortex (PFC), the brain area most central to cognition and implicated in neuropsychiatric disorders. We now aim to use our lab's expertise in category learning and multiple electrode recording in behaving monkeys to address a basic question of neural representation: are PFC neurons cognitive generalists or specialists? This critical question is unresolved because virtually all neurophysiologists train monkeys on a single cognitive problem. We will train monkeys on multiple categorical distinctions and extensively survey neuron activity in three PFC subdivisions (lateral, dorsal, and orbital) using 48 microelectrodes. Two major classes of theories of PFC function make different predictions. Generalist/adaptive theories predict many neurons that each represent multiple category distinctions. Specialist/localist theories predict single neurons dedicated to each distinction. Reality may lie somewhere between. Answering such fundamental questions about neural specificity and localization is how we arrived at our current understanding of sensory and motor processing. Our goal is to provide such an understanding for cognition and the brain area most central to normal cognition. Because categorization is a foundation of cognition, data from this project has the potential to impact on a wide range of behavior and human disorders. Our long-term goal is to provide understanding of this critical cognitive function and by doing so open a path to drug and behavioral therapies that will alleviate neuropsychiatric disorders.